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  • New item   -10.73€Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500
    New item   -10.73€Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500 1
    New item   -10.73€Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500 2
    New item   -10.73€Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500 3
    New item   -10.73€Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500 4

    Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500

    Code: PSW--500
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  • Product description

    Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500

    The PSW--500 is a Sentera Controls adjustable differential pressure switch for the 50–500 Pa range. It monitors overpressure, vacuum or pressure difference in air and, when the set limit is reached, switches a dry changeover contact.

    Key idea:
    This is the simplest and most reliable way to obtain a “pressure present / no pressure” signal: a clogged filter, a stalled fan or insufficient flow is passed straight to the automation or an alarm – without power supply or programming.
    Control range
    50–500 Pa
    Contact
    Changeover, 1.5 (0.4) A / 250 VAC
    Switching differential
    ΔP 20 Pa
    Protection class
    IP54 (with cover)

    Operating principle

    The switch is mounted on a suitable surface. Nozzle P1 is connected to the higher-pressure (or lower-vacuum) point, P2 to the lower-pressure (or higher-vacuum) point. The wires are routed through the PG 11 gland to terminals 1 (NC), 2 (NO), 3 (COM).

    A silicone diaphragm responds to the pressure difference between P1 and P2. The switching threshold is set with a graduated, calibrated knob under the cover. As the pressure difference increases and reaches the set threshold, contact 3–2 closes and 3–1 opens. The switching differential (hysteresis) is 20 Pa. The contact is voltage-free, so it can be connected to a controller input, a relay coil or a signalling circuit.

    Result – the automation or signalling circuit receives a clear binary signal about a clogged filter, a stopped fan or an interrupted airflow. Engineer's note: when the switching threshold is below 50 Pa, the switch must not be mounted upside down – the weight of the diaphragm would affect the switching point. Accuracy per EN 1854 – ≤ ±15 % (min. ±10 Pa), so the switch is intended for monitoring and protection, not for precise measurement.

    Benefits PSW--500?
    A simple pressure monitor that is independent of the power supply, with a changeover contact and a mechanical life of 10 000 000 cycles.

    Technical specifications

    Product type Differential pressure switch (pressure switch)
    Manufacturer / code Sentera Controls / PSW--500
    Series PSW (20–200 Pa / 50–500 Pa; with or without the PVC kit)
    Control range 50–500 Pa (0.5–5.0 mbar)
    Switching differential ΔP 20 Pa (0.2 mbar)
    Contact Changeover: 1 – NC, 2 – NO, 3 – COM
    Switching capacity Max. 1.5 (0.4) A / 250 VAC (VDE 0630)
    Max. operating pressure 10 kPa
    Accuracy ≤ ±15 %, min. ±10 Pa (EN 1854)
    Mechanical life 10 000 000 cycles
    Diaphragm Silicone
    Medium Air and other non-flammable, non-aggressive gases
    Pressure connections + (P1) and − (P2)
    Cable entry PG 11
    Protection class IP54 with cover, IP00 without cover (EN 60529)
    Operating temperature -20…+85 °C
    Storage temperature -40…+85 °C
    Humidity < 95 % rH non-condensing
    Weight 0.1 kg (net)
    Compliance LVD 2014/35/EU, WEEE 2012/19/EU, RoHS (EU) 2015/863, Gas Appliances Regulation 2016/426/EU, EN 1854

    Main functions

    • Adjustable switching point – graduated knob within 50–500 Pa.
    • Changeover contact – NO and NC – suitable for both alarm and interlock.
    • No power supply needed – the relay is mechanical – it works independently of the automation power supply.
    • Long service life – 10 000 000 switching operations.
    • Silicone diaphragm – no outgassing, stable operation.

    Where is it used?

    • Range 50–500 Pa – for monitoring higher-pressure filters and fans
    • Air filter contamination monitoring
    • Fan operation monitoring (flow presence)
    • Overheat protection for duct electric heaters
    • Heat exchanger frost protection in air handling units
    • Control of air and fire dampers

    On-demand operation

    For air handling unit manufacturers.
    The 50–500 Pa range suits monitoring higher-pressure filters and fans, and the switch is supplied without a kit – the nozzles are selected according to the unit.
    For the automation designer.
    The mechanical contact with a 10 000 000 cycle service life works without power and is suitable for safety interlocks.
    For heat exchanger protection commissioning engineers.
    When the pressure drop across the heat exchanger reaches the set limit, the relay signals to start defrosting, and the 20 Pa hysteresis prevents frequent switching.

    Practical application

    If the heat exchanger of an air handling unit frosts up in winter and its pressure drop increases, then the PSW--500, with P1 / P2 connected before and after the heat exchanger, switches its contact when the value set within the 50–500 Pa range is reached, and the automation starts defrosting.

    Application guide: how it is used in practice

    The PSW--500 adapts to different monitoring tasks – only the connection points and the use of the contact change:

    Site What is connected Result Installer's note
    Filter fouling monitoring P1 before the filter, P2 after the filter When the filter becomes clogged, the contact switches and gives a “replace filter” signal Set the limit according to the filter manufacturer's final pressure drop
    Fan operation monitoring P1 on the fan pressure side, P2 in the atmosphere or on the suction side Alarm if the fan is not turning or the belt has broken Use contact 3–2 as "flow present"
    Electric duct heater Relay NO contact → heater enable circuit The heater is switched on only when there is airflow Install according to the heater manufacturer's instructions
    Heat exchanger in winter P1 / P2 before and after the heat exchanger A rising pressure drop indicates frosting – the automation starts defrosting Protect the tubes from condensate freezing

    How to choose the range of a pressure switch

    Switching range / package contents Recommended model
    20–200 Pa, relay only PSW--200 (20–200 Pa)
    20–200 Pa, with PVC connection kit PSW--200-PVC (20–200 Pa, with tubes)
    50–500 Pa, relay only PSW--500 (50–500 Pa) ← this model
    50–500 Pa, with PVC connection kit PSW--500-PVC (50–500 Pa, with tubes)
    Rule: the desired switching point should be closer to the middle of the range: up to ~150 Pa – PSW--200, for higher limits – PSW--500. If nozzles and tubes are not available on site, choose the version with the PVC kit.
    When to choose another solution: version with nozzles and tubes – PSW--500-PVC; for smooth pressure measurement with an analog output – HPS-2 / DPS-2 transmitters; for pressure maintenance by a fan – HPSP-2 / DPSP-2 controllers.

    Pros

    • Mechanical, no power supply required
    • Changeover NO / NC contact
    • Adjustable switching point
    • 10 000 000 cycle service life
    • IP54 with cover

    Cons / limitations

    • Accuracy ≤ ±15 % – not suitable for precise measurement
    • Binary signal only, no analog output
    • With a limit < 50 Pa it must not be mounted upside down
    • Only for air and non-flammable, non-aggressive gases
    • Nozzles and tubes are not included in the kit

    Safety and installation notes

    • Installation and connection must be carried out by a qualified electrician with the power disconnected.
    • Contact load – no more than 1.5 (0.4) A / 250 VAC.
    • Do not operate without the cover – without it the protection class is IP00.
    • Max. operating pressure – 10 kPa; for air and non-flammable, non-aggressive gases only.
    • When the switching threshold is below 50 Pa, do not mount upside down.

    Quick selection guide

    50–500 Pa
    ΔP 20 Pa
    NO / NC
    250 VAC
    IP54
    Suitable when you need:
    • to monitor filter fouling and fan operation;
    • to interlock the electric heater when there is no airflow;
    • to obtain a simple pressure signal without power supply and programming.
    Check before use:
    • whether the desired switching threshold fits within 50–500 Pa;
    • the contact load (up to 1.5 (0.4) A / 250 VAC);
    • whether connection nozzles and tubes are needed.
    Important reminder: The PSW--500 provides only an on / off signal; for smooth pressure measurement or control, a pressure transmitter or controller is required.

    FAQ

    How is the switching pressure set?
    Graduated knob under the cover.
    Which contact closes as the pressure increases?
    As the pressure difference increases, 3–2 closes and 3–1 opens.
    Where do I connect P1 and P2?
    P1 – to the higher pressure (lower vacuum), P2 – to the lower pressure (higher vacuum).
    Is a power supply needed?
    No, the relay is mechanical.
    Are tubes included in the kit?
    No, choose the PSET-PVC-200 or PSET-QF-200, or the PSW--500-PVC version.
    What load can the contact switch?
    No more than 1.5 (0.4) A at 250 VAC (VDE 0630).

    Differential pressure switch | 50-500Pa | changeover contact | 250VAC | IP54 | Sentera Controls | PSW--500

    Sentera PSW--500 – adjustable differential pressure switch 50–500 Pa with a 250 VAC changeover contact and IP54 – for monitoring filters, fans and heaters in ventilation.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.
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